With the various quotes pointing to a shared architecture/shared library, it's pretty safe to assume that they're aiming for that to be implemented with the NX, right?
If you're Nintendo, how would you increase the value of games that are based off of portable hardware?
The power gap should be pretty considerate if we accept the LCGeek rumor of (at least the CPU) being more powerful than the PS4.
I imagine 1080p/60fps for the basic release if Nintendo is serious about this is the minimum they should strive for, but is that enough?
Best case scenario a dev makes a high spec game and then lowers the graphics settings on the portable version while turning on some advanced graphical settings on the console. I believe Xenoblade X had some features turned off to run as well as it did. Building the games with both systems in mind could lead to uncompressed textures and higher poly models as well, but not all games will do that.
2 ideas I had in mind were VR enhanced games and 4K.
VR:
If VR becomes a big hit Nintendo will likely not want to get left behind for a generation. On PS4 it's unlikely to see big AAA multiplatform games being VR compatible, at least not on the normal PS4.
A lot of VR games on it look rather rough due to having to render two screens at 60fps+ locked.
If you take games that, on a technical level, are around early 360 games it should be fairly doable.
4K:
Same principle, running a game in 4K requires very powerful hardware or low spec games. 1080p 3DS games look very good:
And despite looking rather simple, a strong art style and a clear image could work wonders.
Both are strong buzz words especially going into 2017 and onwards. Having the most VR compatible games or the most games running at 4K could create a lot of positive buzz despite just being portable games on a console.